Q3 Postmastery's Email Delivery Benchmark

Third Global Email Delivery Benchmark Report Summary

This third quarterly report evaluates email delivery performance from July to September 2024, with comparisons to the previous Q2 assessment.

The dataset has been expanded further, providing an even clearer snapshot of MBP email delivery performance. This benchmark offers a valuable baseline for senders to compare and enhance their email delivery metrics. Postmastery commits to releasing these benchmarks regularly, with the next report anticipated in early 2025.

Key Metrics

• Delivery Rate: Most ESPs maintain strong performance, with delivery rates still exceeding 99% for many. Seznam.cz continues to excel with near-perfect delivery, highlighting exceptional efficiency.
• Bounce Rate: Mimecast continues to exhibit the highest bounce rate at 5.17%, a slight increase from Q2's 4.41%, pointing to persistent delivery challenges.
• Deferred Rate: Mimecast's deferred rate has risen to 11.12% from 10.39% last quarter, suggesting ongoing issues with server capacity or responsiveness. Google's deferred rates remain stable, focusing on authentication and domain reputation.
• Average Delivery Time: Variability in delivery times persists among providers. Seznam.cz leads with an average delivery time of just 7 seconds, while Orange, despite improvement to 13:00 from 15:55, remains one of the slower providers, indicating potential inefficiencies.

Key Observations

• Rejections due to missing authentication (SPF or DKIM) are now one of the leading causes of Gmail bounces and deferrals.
• The primary cause of deferrals at Google is, once again, the lack of storage space, confirming that many accounts have been deactivated due to users exceeding their quota.
• The growing importance of domain reputation for Google is confirmed by the consistent deferrals tied to the reputation of the SPF or DKIM domain.
• Compared to Q2, the wider spread in Deferred Rate at Google indicates that while most senders are adapting to the new rules, a few are still significantly affected by the tightened policies. This trend is also reflected in the graph showing the distribution of average delivery times across senders.
• Since the last iteration of our benchmark, the bounce rate and deferral volume at Yahoo have dropped significantly. This may indicate that Yahoo has adjusted its thresholds and/or that most senders are adapting to the new policies.